There is mounting evidence that the materials typically used in mouth guards do not provide adequate protection. Despite widespread use of mouth guards in sports, there are more than one million dental injuries per year, and dental injuries are the most common type of orofacial injuries in sports.
According to the American Dental Association (ADA), the lifetime costs for treatment of serious dental injuries are $15,000-$20,000 per tooth. Individuals who damage a tooth end up with multiple visits to the dentist, with down stream periodontal disease or other dental problems often leading to the need for implants. This brings the annual cost for dental injuries in sports in the USA alone to $500 million.
Dental injuries are also quite common in hospitals during transoral procedures. By way of example, a transoral procedure may be such as, but not limited to, an intubation or a rigid or flexible endoscopic procedure.
Dental injuries during transoral procedures affect approximately 1% of patients, which corresponds to 150,000 patients/year and an annual cost of $75 million. Furthermore, dental injuries during intubation are the leading reason for litigation against anesthesiologists.
Inexpensive mouth guards tend to have a poor fit, leading to low compliance of mouth guard use. Professional-grade mouth guards require fitting by dentists, making the mouth guards very expensive; but even these professional-grade mouth guards tend to be bulky, and restrict breathing and verbal communication.
Since typical mouth guards are so uncomfortable, athletes frequently take them out and put them back in. The repeated handling of saliva-coated mouth guards leads to contamination of mouth guards from hands and fingers with pathogens.
Clearly, a better mouth guard is needed that is thin enough so that does not impede breathing and communication, and does not tempt athletes to frequently remove it, while providing a much higher degree of protection than the state-of-the-art.
There are sports activities where high-velocity impact events occur that reach peak force very quickly, within milliseconds (e.g. getting hit by an ice hockey stick or puck). While in other sports such as skateboarding, a crash can lead to landing on the chin or cheek. The peak force resultant from such an impact will be lower, but applied over a larger area of the face.
In medical applications, such as intubation of patients during surgery, the peak forces are reached even more slowly but maintained over extended time periods, i.e. by laryngoscopes and rigid endoscopes inserted into the patient's mouth and throat. Similarly, in bruxism (night time teeth grinding), the forces are applied primarily in specific locations within the dental region, in the rear of the mouth in the molar region.
A variety of materials have been used for mouth guards, including polyvinylacetate-polyethylene or ethylene vinyl acetate copolymer (EVA), latex rubber, polyurethane, polyvinylchloride, and acrylic resin. The current paradigm in materials selection for commercially available, inexpensive mouth guards is based on the concept that soft materials, such as ethylene vinyl acetate (EVA), provide protection by cushioning the teeth upon impact. However, in order to achieve the required degree of protection, relatively thick layers of polymer have to be used, with typical thicknesses in the range of 4 mm since these materials are highly compressible and thus tend to “cave in” and deform under impact. These mouth guards also usually fit very poorly.
Better fitting, professional-grade mouth guards can be made from harder acrylic resins. This usually requires a visit to the dentist, where impressions are taken, so that the mouth guard can be fabricated in a dental laboratory. This process is time consuming and costly, a major impediment to consumer acceptance.
Conventional mouth guards require the users to bite down on the mouth guards to keep them in place. The approximately 4 mm thickness of conventional mouth guards makes it almost impossible to wear them on both the upper and lower teeth. Furthermore, since the mouth guards are so bulky, they hinder breathing and verbal communication. It is also almost impossible to drink with the mouth guard in place.
For sports where very high impact energies and velocities may be encountered, and for clinical applications where high stresses are encountered when intubation laryngoscopes and endoscopic instruments inserted into the throat apply pressure on the teeth, it is necessary to develop a much stronger mouth guard that can more effectively dissipate the forces.